1. Field of the Invention
This invention concerns a velocity measuring method and device based on the diffusion of light by particles traversing a small measuring volume formed in a highly illuminated stream of a gaseous/liquid fluid and more specifically concerns a method and device for velocity measurement using an array, or mosaic, of optical fibers and not requiring the coherent properties of light.
2. Description of the Prior Art
Fringing laser velocimeters are presently able to simultaneously measure three components of speed in very turbulent flows. They require the use of a very complex, costly system for spitting a coherent beam, which must be aligned for each application. Moreover, they cannot take measurements at less than ten millimeters from a wall struck normally by the beams.
Two-point velocimeters can measure very close to walls, but only in flows with very little turbulence (.tau..sub.u &lt;10%). The two-line velocimeter, although able to measure close to walls in more turbulent flows (.tau..sub.u .perspectiveto.20%), does not operate in recirculation areas where the orientation of the velocity vector exhibits considerable fluctuation: as can be readily understood, any particle moving parallel to the lines will not be measured.